28 Jul 2009

The recent upturn in the sunspot count seems to have stalled a bit, although the rolling average does appear to point to an upturn which should result in improving conditions this autumn and winter. Solar flux levels remain below 70 still and don't seem in a hurry to rise.

However, 6m is still lively with sporadic-E and continues to liven up this magic band.

27 Jul 2009

This afternoon I worked G3PTQ in Bottisham, 6kms away with the 50mW Sixbox AM transceiver. Report was RS41 (weak, but 80% readable). Then Terry mentioned he was using a low horizontal dipole, so signals could easily have been some 10-20dB (2-3 S points) stronger had he had a vertical antenna. This little transceiver is definitely proving useful for local 6m contacts.

25 Jul 2009

For a few hours today I managed some operating on 10m QRP in the IOTA contest. No great DX (best was Cyprus) but I did work a couple of stations when running just 500mW pep. They didn't appear to notice the low power and still gave me 59! For a little while I tried calling some of the stronger stations with 50mW pep, but in the limited time I had the best I got was a G3X.. QRZ? at that power. With 50mW on CW it would have been quite easy.

Interestingly I heard GD (Isle of Man) and GJ (Jersey) on 10m SSB today. Both are usually too near to work or hear. Unfortunately I didn't managed to raise them. Pity as they would have been new DXCC entities for me on the band.

23 Jul 2009

This evening I managed 16kms contacts with both the SixBox 6m 40mW AM transceiver and with the Fredbox 2m 10mW AM transceiver. QSOs were from Aldreth, Cambs, to Swaffham Prior.

Signals from the SixBox were copied by Andrew G6ALB when I was TXing with a 6m 1/4 wave antenna on a magmount on the car roof. On the superregen RX there was solid copy of G6ALB's 6m AM signal. Andrew uses a Diamond V2000 vertical, which recent discussions have confirmed are NOT as effective as a true 1/2 wave vertical on 6m. Clearly if Andrew had even a 2 el beam the QSO would have been a very decent one.

After finishing on 6m QRP, we moved to 2m AM to try some tests with the 2m Fredbox. A solid QSO was quickly achieved with the 10mW Fredbox using the 6m 1/4 wave antenna on the car magmount. This acts as a 3/4 wave antenna on 2m. I then tried the same antenna on the Fredbox handheld. Again, a solid 2-way QSO at 16kms distance. Switching over to a 1/4 wave whip on the handheld Fredbox resulted in a weaker, but just usable signal and QSO (same signal level as on the 6m SixBox). Finally, I tried the Fredbox handheld with a small helical antenna. Although Andrew could just detect this, no real QSO was possible.

So, with the V2000 in use at the far end of the contact, 40mW AM on 6m was not as strong as 10mW AM on 2m. Notheless, it was fun to give both rigs a portable outing and make some contacts.

The picture shows me during the Fredbox QSO using the 3/4 wave whip on the Fredbox.

Last night I gave my "Kitchen Table Minimalist Radio" talk at the Peterborough Radio Club. Everyone was very welcoming and, to my surprise, there was a very good number of people there to hear me. Afterwards quite a lot of the group came up to take a look at some of the homebrew gear that I had made and talked about.

One thing that struck me, again, is how few young people there were there. Having given similar talks in 3 clubs in East Anglia now, one can count on one hand the number of youngsters (boys/girls) at the meetings. OK, it could be my subject did not appeal to them, but I think this is a more general issue and one that we HAVE to address seriously or the hobby will die with us in another 20 years or so.

The RSGB (and I suspect the ARRL) have initiatives such as GB4FUN to help this shortfall of youngsters coming into the hobby. I feel that it is in the schools, youth clubs and scout groups that we have to inspire kids with the magic of radio.

Even after 50 years, radio still is magical for me. I just wish I could help to "spread the word" to today's young people. Also, industry NEEDS new radio engineers before the oldies die out!

22 Jul 2009

Several recent local tests on 6m lead me to believe the V2000 triband vertical is not that good for local working. It is fine for DXing but signals around 15-25 miles away are weaker than I'd expect. Maybe the polarisation is not as truly vertical as I had believed? I can access the 6m repeater 25 miles away OK and can work stations, but at levels lower than I would have expected. Essentially the V2000 should be like a vertical halfwave on 50MHz, so this is a bit puzzling. In the past I had assumed it to be a pretty good antenna, but maybe not.

20 Jul 2009

Back home in Cambridgeshire now and, sadly, was unable to find anyone within a 15-20 mile radius when in S.Devon with whom to test the SixBox QRP AM rig. This despite calling for several DAYS on the local 6m and 2m repeaters.

The Torbay 6m FM repeater was a good signal and I could access it well, but I heard not one person using it! No-one even replied to a call through it.

I had plenty of 6m DX QSOs on SSB using the magmount on the car and 5W though, and heard (but not worked) some remarkable transcontinental DX on the band from South America.

So, back to more modest aims, I shall be on the lookout for stations in East Cambs to do further range testing the SixBox. Let me know if you have 6m vertical and AM and are likely to be workable with 50mW AM from East Cambridgeshire so we can try a test. I am located in Burwell and have a reasonable takeoff to the west and north.

19 Jul 2009

This Wednesday I am giving my "Kitchen Sink Radio" talk at the Peterborough Radio Club. I will put the presentation on my website after the event. At the moment I am hoping my wife's WinXP PC survives as it has two keys which packed up last week. I need this PC for the slideshow. Arghhh!!

16 Jul 2009

For the last few days I have been in South Devon on holiday. Some evenings I have been out looking for skeds with the SixBox 6m QRP AM transceiver but two tests failed even with 2W AM from the FT817 and the 1/4wave magmount, so no QSOs with the baby rig yet. However, I managed several European DX QSOs with 6m QRP SSB, all with good reports.

Last night was exceptional on 6m: YV4DDK, FM5AA and 9Y4D all coming through at good strength (at times) on 6m SSB with just a 1/4wave magmount antenna! Although I tried calling the YV4 at one point I knew it was pointless with all the super-QRO stations with big beams calling them. Still, it was good to HEAR such super-DX on 6m (8000kms) with such a simple portable station.

11 Jul 2009

Two local tests with stations on 6m AM have shown just how noisy the band can be when using this mode. M1KTA was 18kms away and M1MAJ around 15kms yet both were not strong on the vertical V2000 antenna on 6m AM even when they were using FT817 rigs at 2W AM. We were going to try the SixBox but signals would have been too weak. Switching to USB made a lot of difference (better) unsurprisingly, as the noise level reduces with the bandwidth.

This goes to show how AM signals do need to be strong to overcome the band noise: when signals are a decent level AM is a fine mode, but it can be hard work when they are very marginal with lots of noise in the background.

9 Jul 2009

Anyone around near Cambridge/Newmarket/Ely with a 6m vertical antenna who can help me range-test my very simple homebrew 6m QRP AM rig in the next couple of days? SixBox details on this blog and my website. It is working OK but I want to find out how far it gets locally.

Freq: 51.125MHz (sorry only xtal I have at the moment)Power: 50mW AMAnt: V2000 verticalLoc: Burwell, 10m NE of Cambridge, JO02DG

8 Jul 2009

This evening I had a third QSO with G6ALB using the SixBox 6m 50mW AM transceiver. The main aim was to test the receiver sensitivity since fixing an issue last evening. Andrew first called me using his FT817 on the lowest AM power setting and he was good copy. He then switched over to a modulated AM signal generator at 7dBm level (5mW). This was easily copied on the superregen RX. Even with a 10dB pad in at my end I could still copy the signal i.e. at an equivalent of 0.5mW from Andrew 2 miles away. So, without accurate test equipment I can safely assume the RX is detecting low uV level signals. I must work out the path loss.

Having got the SixBox working pretty well it now remains to see how far it can reach. I am really pleased with this simple project. It is very satisfying to work people on AM using really simple homemade equipment built with minimal test equipment and using parts which cost very little.

The current TX frequency is 51.125MHz. I need to buy a crystal for the 6m AM working frequency (50.57MHz in the UK or 50.4MHz in the USA).

7 Jul 2009

Noticed the sunspot numbers trend recently? Whereas a few months ago there were weeks and weeks without a spot, now there are spots on a high proportion of days and the general level of active cycle 24 spots is creeping upwards. All this bodes well for this autumn when I hope we'll see some F2 transatlantic propagation on 10m again on many days, with plenty of US and Canadian stations workable with QRP - a sure sign that the old sun is waking up.

6 Jul 2009

RS59 from G6ALB this evening with the SixBox 50mW AM transceiver. In putting the transceiver in its box and adding the RX tuning I inadvertently removed the coupling cap between the RF and and detector stage so the RX was a little bit deaf. I will add this back tomorrow and expect sensitivity to be back to low uVs level. Even without it, I could hear signals of 2-3mW out from Andrew.

Next week I am in Devon on holiday, so will be looking for some 50MHz AM QSOs with the SixBox from clifftop highspots. I will set up some 6m AM skeds using the local VHF and UHF repeaters.

4 Jul 2009

A 10m AM net has been started in South London, UK by Gary G7IRG. It meets on 29.05MHz (AM mode) on Wednesdays at 9pm local time. Last week the net had 3 people on: G7IRG, G0KRT and M0GPG. If you live in this area, or indeed anywhere, why not see if you can hear the net and give them a call?

When 10m is wide open, as it will be in a couple of years time, the band between 29.00 and 29.1 MHz will be filled with AM stations from around the world.

6m is a band ripe for exploitation when there is no DX around. When there is sporadic-E or F2 DX about, people use the band in thousands and some have worked DXCC. However, when conditions are not good, it is left to a few dedicated enthusiasts to work random MS and tropo and ionospheric scatter mode QSOs using QRO with modes like JT6m. The amount of LOCAL 6m activity, at least here in the UK, is very low indeed.

We have 2MHz of band in the UK (4MHz in the USA) and it is a pity more use is not made of this fine band for local QSOs using simple QRP homebrewed equipment. It is an ideal band for QSOs up to around 20 miles or so and much quieter than 160m or 80m, which can be very noisy these days.

The website of Kazuhiro SunamuraJF1OZL is magic and contains some superb ideas for QRP enthusiasts. Every time I return to this site I find something to enjoy and to inspire me. Take for instance the 3 transistor 6m transceiver he describes: it is wonderful. Kazuhiro San, if you read this THANK YOU for your great ideas.

Having finished my SixBox 6m AM transceiver, my mind is now turning to ideas for either a 10m or 6m QRP DSB transceiver. I have already breadboarded a 10m version in separate sections (RX based on the Neophyte RX, a DSB TX based on a single balanced diode mixer), but I have still to breadboard a mixer-VFO based on the NE602 which would be useful for either band. Actually a fundamental crystal x2 would give around 25-30kHz shift on 28MHz and around 50kHz on 50MHz, so this may be a simpler, and adaquate, route. However crystals "to order" are expensive these days, although the spec (temperature, cut frequency accuracy, etc) would be very low.

Today I noticed another 6m DSB schematic from a Japanese ham. There are plenty of good ideas from JA land where, despite commercial rigs, homebrewing is still in strong. See http://www6.plala.or.jp/jr8dag/micro6dsb/mi6dsb02.htm for JR8DAG's schematic. In my view, this is a rather complex schematic and I am sure it could be simplified.

1 Jul 2009

Today I complete this project and put the 50mW AM transceiver into a small diecast aluminium box. Using a 9V battery inside the box the rig puts out about 20mW. From an external supply it is about 50mW. The polyvaricon tuning capacitor works very well and the RX tunes from around 45MHz to 70MHz. Already it has been useful as an indicator of Band 1 activity.

Overall, I am pleased with this little transceiver. It was all done with the most basic of test equipment and is a circuit that should be easy to copy. Now to try to get some local 6m AM activity going! It would be very nice to make a PCB for this project. I'm thinking about it....

My next project is either the long intended 10m DSB rig or a DSB version of this 6m AM rig. However, to be useful this would need VXO control and a 3rd overtone xtal will not pull very far.